I. Field of the Invention
The present invention relates generally to a wireless communication system, and more specifically, to a method and apparatus for reducing frame error rate (FER) in a wireless communications system.
II. Related Art
When delivering data over a wireless link that has a relatively poor FER (for example, greater than 1%), many methods of retransmitting data exist for achieving as low a FER as a data service demands. For example, a cyclic redundancy check (CRC) can be performed at a receiving end of a link to check the integrity of a block of data. CRC is a well known method of establishing that data was correctly received in data communications. A CRC character is generated at a transmitting device and appended to a data block. The receiving end makes a similar calculation and compares its results with the added CRC character. If there is a difference, the receiving end requests retransmission of the data block.
For example, the use of protocols such as Automatic Retransmission reQuest (ARQ) can be used for retransmission of data blocks. In ARQ, the transmitting device encodes an error-detection field (for example, a CRC field) based on the contents of a data block. The receiving end recalculates the check field and compares it with that received. If they match, an acknowledgment (ACK) is transmitted back to the transmitting device. If they don't match, a negative acknowledgment (NAK) is returned, and the transmitting device retransmits the message.
The above discussed method is satisfactory for transmitting many types of data. However, these methods of achieving low FER cause increased latency due to the retransmission of data blocks. Such increased latency is not acceptable when transmitting certain types of data, such as real time digitized voice, or any other type of latency sensitive data. More specifically, the retransmission of data blocks causes delay times that are both higher on average and have greater variance than the requirements for many latency sensitive systems.
What is needed is a method and apparatus for delivering data having low FER without having increased latency. In other words, there is a need for a method and apparatus for reducing FER without relying on the retransmission of data blocks.